Soil science 1

• Components of the Global Ecosystem:

  • Atmosphere: air surrounding the Earth
  • Biosphere: environment where living organisms are found and interact
  • Hydrosphere: total body of water on or close to the Earth's surface
  • Lithosphere: upper layer of the solid Earth
• Pedosphere:

  • The envelope of the Earth where soils occur and soil-forming processes are active
  • Located at the interface of the lithosphere, biosphere, atmosphere, and hydrosphere
  • Earth's living skin
• Most abundant elements in the crust:

  • O: 46%
  • Si: 28%
  • Al: 8%
  • Fe: 5%
  • Ca: 3.6%
  • Na: 2.8%
  • K: 2.6%
  • Mg: 2.0%
• What is soil?

  • Living, dynamic system at the interface between atmosphere and lithosphere
  • Forms in response to forces from climate, living organisms, and parent material over time
  • Collection of natural bodies on Earth's surface supporting plants
• Soil Dimensions:

  • Classic Concept: 3-dimensional body with length, breadth, depth
  • Modern Concept: space-time structure with length, breadth, depth, time dimension
• Boundaries of soil:

  • Upper Boundary: air, shallow water, live plants, or loose plant material
  • Lateral Boundary: deep water or barren areas
  • Lower Boundary: depth of effective soil weathering
• Soil as part of Landscape & Ecosystems:

  • Landscape: three-dimensional section of Earth's surface with specific topography, rocks, soil, water, flora, and fauna
  • Ecosystem: interacting system of biologic community and non-living environment
  • Soil is the link determining healthy/ecosystem diversity
• Functions of the Soil:

  • Water supply and engineering
  • Habitat for soil organisms
  • Medium for plant growth
  • Recycling system for nutrients and organic wastes
  • Engineering function for building foundations and construction materials
• Why Study the Soil?

  • To conserve and utilize soils properly
  • To understand how soil properties affect various uses
  • To modify soil properties for specific uses
• Two concepts of the study of Soils:

  • Pedology: study of soil origin, classification, and description
  • Edaphology: study of soil from the standpoint of plant growth
• Soil Science History:

  • Originally a branch of Geology evolving into a Natural Science
  • Soil Science applications towards agriculture and environmental research
  • Soil Science as a natural science with wide applications in forestry, agriculture, ecology, geography, and environmental science
• Three Periods in the Development of Soil Science:

  • Ancient Period: early soil studies by Roman, Chinese, Greek, and Roman thinkers
  • Pre-Soil Science Period: contributions by Gilbert, Liebig, and Darcy
  • Early Soil Science Period: contributions by Fallou, Dokuchaev, Jenny, and Hilgard
• International Union of Soil Sciences (IUSS):

  • Global scientific organization of soil scientists and practitioners
  • More than 50,000 members worldwide
  • Full member of the International Council for Sciences